Organ additive prevoicing system



Aug, l, 1967 A. c. YQUNG ORGAN ADDITIVE PREVOICING SYSTEM 2 SheeziLs--Sheef l Filed July 20, ,1964

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Aug. 1, 1967 Filed July 20, 1964 QW.. am. N@ ,KWWL www r UnitedA States Patent O 3,334,173 ORGAN ADDITIVE PREVOICING SYSTEM Alan C. Young, Park Ridge, Ill., assignor to Hammond Organ Company, Chicago, Ill., a corporation of Delaare Filed July 20, 1964, Ser. No. 383,728 5 Claims. (Cl. 84-1.09)

This invention relates -generally to electrical musical instruments wherein a given tone may be produced by synthesis of the fundamental tone with various proportions of its harmonics. More particularly, the invention inite combinations of the fundamental tone and various proportions of the harmonics of the fundamental.

The prior art, for example, U.S. Patent No. 1,956,350, to Hammond, contains teachings of musical instruments, such as electric organs, wherein various electrical tone signals of different frequencies produced by tone signal -generators are combined in certain proportions of intensity in output circuits controlled by tab switches, whereby tones Simulating various conventional musical instruments, such as the oboe, horn, or strings, may be sounded through the output system. Although some of the instruments of the prior art are capable'of producing music of high quality, and have enjoyed considerable public acceptance, the performance of many is limited in that the voices controlled by the various tabs may be played only separately, not cumulatively, so that they are incapable of producingV many of the desirable musical effects obtainable by pipe organs. For example, in pipe organs the loudness of a tone proceeding from a pipe of given size is constant when properly played and, accordingly, crescendo and sforzando effects cannot be produced simply by increasing the ow of air to the pipes. Therefore, to play crescendo or sforzando, the pipe organist adds voices to the voice or voices already being played, for crescendo the extra voices beind added gradually and sequentially, for sforzando the extra voices being added substantially simultaneously. An electric organ in which the various voices may be played only separately therefore does not lend itself to playing crescendo or sforzando by the`technique used-by the pipe organist.

It is an object of the invention to provide a system for use in electrical musical instrumentswherein a plurality of .'voices, each composed of selected proportions of intensity of dierent members of a series of harmonically related electrical tonev signals, may be played individually or cumulatively through the output system of the instrument.

A/further object is tolprovide a system in'accordance With the Aforegoing object, wherein voices from a selected group which are not being played may be added to voices of such group which are being played, to produce 'crescendo or sforzando expression.

A further object is to provide a prevoicing system for use in electrical musical instruments of the organ type adapting the organ to producing musical tones in a plurality of voices, and further adapting the organ to be played in accordance with the technique of the pipe organist.

Other objects and advantages of the invention will be i preferred embodiment thereof, taken in conjunction with the accompanying drawings wherein like numerals refer to the same or identical parts in all the figures.

In general, the invention comprises a number of multiple-contact switches, or gang switches, each of which includes a plurality of movable contact members and a corresponding number of fixed contacts associated respectively with the movable contact members. The movable contact members in each gang switch are arranged in a stack, and the number of such stacks of movable contact members corresponds to the number of playing keys in all keyboards of the organ, both manual and pedal. Each set of movable and ixed contacts in each of the gang switches is in a circuit having an electrical tone signal generator on one side of such set of contacts, and the tone signal generators associated respectively with such sets of contacts in each such gang switch are related in frequency in the manner of a -fundamental note to its harmonics. The other side of each such set of contacts in a gang switch is connected to at least one common conductor leading to the output of the instrument which includes-a conventional electroacoustical translating means. Each such common conductor is connected to a plurality of such sets of contacts in each gang switch, thereby collecting tone signals of different frequencies which are adapted to be played as a combination through the output of the instr-ument in simulation of a conventional musical instrument, such as the cello, or to produce some other desirable musical effect.

Each of the common conductors is connected to the output through a switch, whereby the combined frequencies in the several common conductors may be selectively passed to the output. In those common conductors wherein frequencies are collected which are intended to be combined in playing crescendo, a second switch is provided, in parallel with the other switch, so that by closing the second switch the signals collected in such conductor pass to the output even if the other switch is open. Conventional switch control means are provided for operating all of such second switches in a given sequence, to close the circuit between the common conductors and the output, either rapidly enough so that such'second switches are closed substantially simultaneously, or at intervals within the control of the player.

In the accompanying drawings,

FIG. 1 is a schematic wiringv diagram illustrating circuitry for carrying out the invention; and

FIG. 2. is a schematic wiring diagram of a voice mesh used in the system depicted in FIG. 1.

Referring to the drawings, there is shown in FIG. 1 a multiple-contact switch or gang switch 10, representative of the type used in the present invention, the switch comprising a plurality of movable contact members 12 arranged in a stack, and a corresponding number of bus bars 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, Z6 and 27, the bus bars serving as common fixed contacts for a plurality of stacks of such movable contact members. The gang switch 10 may be of conventional construction, such as the type disclosed in the yabove mentioned Hammond patent, and includes an actuator member (represented by the broken line 30) connected to or adapted to engage each of the movable contact members 12, whereby movement of the actuator member causes all the movable contacts to move in unison. The actuating member 30 is adapted to be depressed, and thus to move all the movable contacts 12 into engagement with their respective bus bars, when a particular playing key on one of the keyboards of the instrument is depressed. To produce such action a relay 32 is provided having a solenoid 34, the armature of which is operatively connected to the actuator member 30, as shown, and adapted to move all the movable contacts of the gang switch into engagement with their respective bus bars when the relay is energized. The relay is connected through a switch 36 to a suitable energizing D.C. power source, indicated as +7 v., the switch 36 being operable by a playing key 38 in one of the keyboards of the instrument.

Each of the movable contact members 12 is connected to a tone signal generator for producing a tone signal which is useful in combination with another tone signal 0r signals to produce one of the voices adapted to be played by the musical instrument. In the embodiment -illustrated in EIG. 1, the frequencies necessary to produce the desired voices are the fundamental, the second to the twelfth harmonics, inclusive, the sub-third harmonic and the sub-fundamental and, accordingly, the movable cont'act members 12 of the gang switch 10 are connected respectively to generators which generate such tone signals for the particular playing key 38 involved, the bus bars of the several individual switches of the gang switch being identified in FIG. 1 by the harmonic relations of the generators to which they are connected.

Of the fourteen tone signal generators required only three are shown schematically in FIG. 1 since all may be identically illustrated, and their repetition in the drawings is not necessary for a clear understanding of their function and relation to the several movable contact members 12. These three illustrated tone signal generators are indicated as 40, 41 and 42, and each is shown connected by a conductor 56 through a decoupling impedance member, such as a resistor 58, to one of the movable contact members 12 of the gang switch. The output Iof each of the tone signal generators is connected in parallel to a plurality of the conductors 56 for providing the tone signal of the particular generator to other gang switches operable by other playing keys, wherein the frequency of that generator is required as a component of the voice to -be synthesized from frequencies supplied to such other gang switches. The boxes 43 to 53 in FIG. 1 represent the remaining eleven generators, of the fourteen mentioned above, together with their parallel resistor connections for connection to the bus bars 16 to 26, as shown, and to contact members 12 of other gang switches 10, as just described. The tone signal generators may be of any conventional type, for example, the well known tone frequency sources of the transistor type, the tone wheel generators disclosed in the above mentioned Hammond patent, or the electronic oscillators disclosed in U.S. Patent No. 2,645,968 to Hanert.

Each of the bus bars 14-27 is connected to at least one of a plurality of common conductors, later to be described, whereby currents of different frequencies separately impressed on the several bus bars are combined to produce the tones characteristic of the various voices to be produced.

When tone signal generators having outputs of low power level, e.g., the tone wheel generators disclosed in the above mentioned Hammond patent, are used as the generator for supplying tone signal frequencies to the gang switches, an amplifier 60 of conventional design is preferably provided to raise appropriately the power level of the signals taken from each of the bus bars. When tone signal generators having outputs of high power level, e.g., the electronic oscillators disclosed in the said Hanert patent, are used as the generators herein, amplifiers, such as the amplifiers 60, are not essential, although they may still be used if desired since they increase the allowable variation in the voicing meshes (presently to be described) without unbalancing the circuit.

The voicing mesh described below is intended to illustrate voicing meshes suitable for synthesizing various pipe organ tones using various intensities of various frequencies harmonically related to tones as fundamentals throughout the frequency range of a pipe organ. The particular voicing mesh described below illustrates the combination of various intensities of different frequencies related to fundamental tones within the range of the great manual of Ia multikeyboard organ, to produce simultaneously twelve specific pipe organ tones.

The several bus bars 14-27 (or the outputs of their associated amplifiers 60, if amplifiers are used) are connected respectively through blocking capacitors to various common conductors in which various preselected frequencies are combined in preselected intensities. Thus, the bus bar 14 is connected by a line 61 through a blocking capacitor C62 and an impedance element R63, here shown as a resistor, to a conductor 64 leading to the output of the instrument. Similarly, the bus bar 15 is connected by aline 66 through a blocking capacitor C67 and a resistor R68 to the same conductor 64. Other similar connections will be indicated presently. The cornmon conductor 64 collects signals of proper frequency and intensityto produce, illustratively, a tone simulating the sixteen foot Bourdon tone of the pipe organ.

In the illustrated voicing mesh, eleven other common conductors 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, and 79 are provided to combine, similarly, signals of various frequencies and intensities to produce respectively -tones simulating the eight-foot Trumpet, Mixture IV, two-foot fifteenth, 22/3-foot Nazard, four-foot Gedekt, four-foot Octave, eight-foot Cello, eight-foot Dulciana, eight-foot Gross Flute, eight-foot Melodia and eight-foot Open Diapason tones of the pipe organ. To accomplish this, the Lbus bar 16 is connected by line 80 through a blocking capacitor C81 and by parallel connections through resist-ors R82, R83, R84, R85, R86, R87, and R88 respectively, to common conductors 69, 75, 76, 77, 78, 79 and 64; bus bar 17 is connected by aline 91 through a blocking capacitor C92 Iand by parallel connections through resistors R93, R94, R96, R97, R98, R99, R101, and R102, r'espectively, to common conductors 69, 73, 74, 75, 76, 77, 78, and 79; bus bar 18 is connected by a line 103 through a blocking capacitor C104 and by parallel connections through resistors R106, R107, R108, R109, R111, R112, and R113, respectively, to common conductors 69, 72, 75, 76, 77, 78, and 79; bus bar 19 is connected by -a line 114 through a blocking capacitor C116 and by parallel connections through resistors R117, R118, R119, R121, R122, R123, and R124, respectively, to common conductors 69, 71, 73, 74, 75, 76, and 79; bus bar 20 is connected Iby a line 126 through a blocking capacitor C127 and by parallel connections through resistors R128, R129, R131, and R132, respectively, to common conductors 69, 75, 77, and 79; bus bar 21 is connected by -a line 133 lthrough a blocking capacitor C134 and by parallel connections through resistors R136, R137, R138, R139, R141, R142, and R143, respectively, to common conductors 69, 70, 72, 73, 74, 75, and 79; bus bar 22 is connected by a line 144 through a blocking capacitor C146 and by parallel connections through resistors R147, R148, and R149, respectively, to common conductors 69, 75, and 79; bus bar 23 is connected by ya line 151 through a blocking capacitor C152 and by parallel connections through resistors R153, R154, R156, R157, R158, and R159, respectively, to common conductors 69, 70, 71, 74, 75, .and 79; bus bar 24 is connected by a line 161 through a blocking capacitor C162 and by parallel connections through resistors R163, R164, R166, and R167, respectively, Ito common conductors 69, 70, 72, and bus bar 25 is connected by a line 168 through a blocking capacitor C169 and by parallel connections through resistors R171, R172, land R173, respectively, to common conductors 69, 70, and 75; bus bar 26 is connected by a line 174 through a .blocking capacitor C176 and by parallel connections through resistors R177, R178, and R179, respectively to common conductors 69, 70, and 75; and bus bar 27 is connected by a line 181 through a blocking capacitor C182 and by parallel connections through resistors R183, R184, R186, R187, and R188, respectively, to common conductors 69, 70, 71, 72, :and

`to blades 191 of manually operable double throw switches 192 and 193, and the conductors 69, 70, 72, 73, 74, 75, 76, 77, 78, and 79 are connected respectively to the blades 194 of manually operable double throw switches 196, 197, 198, 199, 200, 201, 202,203, 204, and 205. The blades 191 and 194 are adapted to engage one or the other of the illustrated upper and lower contacts provided with eachof the switches containing such blades. The upper contacts of switches 192 and 193 are connected to ground, and the lower contacts of such switches are connected to a common conductor` 206. The upper contacts of switches 196, 197, 198, 199, 200, 201, 202, 203, 204, and 205 are connected respectively to blades 207, of double throw switches 208 209, 210, 211, 212, 213, 214, 215, 216, and 217, the said blades 207 being adapted to engage one or the other of the illustrated upper and lower contacts provided with each of such switches. The lower contacts ofv switches 197, 198, 199, 203, and 204 are connected to the common conductor 206, while the lower contacts of switches 196, 200, 201, 202, and 205 are connected to a second common conductor 218.

The upper contacts of switches 208-217 are each connected to ground, while the lower contacts of switches 209, 210, 211, 215, and 216 are connected in parallel with with the lower contacts of switches 197, 198, 199, 203, and 204 to the common conductor 206. The lower contacts of switches 208,212, 213, 214, and 217 are connected in parallel with the lower contacts of switches 196, 200, 201, 202, and 205 to the common conductor 218.

The common conductor 206 conducts the signals impressed thereon to the output 219 of the instrument, preferably through a wide vibrato circuit indicated at 221, the output 219 including percussion and swell control, amplier, speaker, and other circuits which may be desired which are well known in the art and form no part of the present invention. The common conductor 218 conducts the signals impressed thereon to the output 219, preferably through a narrow vibrato circuit indicated at 222. The vibrato circuits 221 and 222 are not specifically described herein since they are also well known in the art and form no part of the present invention.

The individual switches 208-217 are embodied in a gang switch of conventional construction, wherein a single actuator controls the movements of all of the blades 207 in such a way that they are moved in sequence out of their engagement with their respective grounded contacts (null position) and into engagement with their other contacts (operative position). Inasmuch as such gang switch arrangements are well known in the art, the present embodiment thereof is shown schematically in the drawings, and in FIG. 1 the actuator for actuating the several switch blades 207 is .depicted by the broken line 223. The operation of the gang switch comprising individual switches 208-217 is such thatwhen the actuator 223 is depressed (i.e., moved downwardly as viewed in FIG. 1) the several blades 207 are sequentially moved out of engagement with their upper contacts and into engagement with their lower contacts, the sequence beginning with the top switch 217, and when the actuator 223 is raised the reverse sequential action occurs, with the blade 207 of the bottom switch 208 being rst to move out of engagement with its lower contact.

The upper end of the actuator 223 is operatively connected to a crescendo pedal 224 operated by the player, whereby the actuator 223 may be moved at any desired rate of speed so that the intervals between successive engagements of the blades 207 with their respective upper or lower contacts (depending on whether the actuator 223 is moved upwardly or downwardly) is completely under the players control.

The upper end of the actuator 223 is also operatively connected to the armature of a solenoid 226, the c-oil of which is connected through a switch 227 to a suitable energizing D.C. power source indicated as +7 v. When 6 the solenoid 226 is energized by closing the -switch 227, the armat-ure thereof substantially instantaneously depresses the actuator 223 to its lower limit, so that the engagement of the several blades 207 of the switches 208-217 with their lower contracts is substantially simultaneous. Con-v versely, when the switch 227 is opened, the spring (not shown) in the solenoid 226 very quickly retracts the armature, at the same time raising the actuator 223, so that removal of the blades 207 from engagement with their `respective lower contacts is also substantially simultaneous.

As noted above, the musical instrument is provided with a number of stacks of movable contact members 12 corresponding to the number of playing keys in all of the keyboards of the organ. In FIG. l the stack of movable contacts 12 associated with the bus b-ars 14-27 in the Iillustrated gang switch 10 is for the playing key A4 (as noted on the key 38) -of the great manual keyboard of the organ. The movable contact 12 positioned third from the top of the stack in FIG. 1 is connected through a line 56 to the tone signal generator for generating the fundamental frequency for the note A4, i.e., 440 vibrations per second. The top movable contact 12 is connected to a current frequency source, such as the tone signal generator 40, for providing the frequency of the subfundamental Itone (i.e., A3=220 vibrations per second) and the other movable contact members 12 are similarly connected respectively through lines 56 to the other indicated current frequency sources for supplying respectively lthe current frequencies of the various harmonics of A4 noted in relation to the several bus b-ars in FIG. 1.

A current frequency source must be provided for each note played by the instrument. In addition, current frequency sources for generating frequencies corresponding i to notes higher and lower lthan those which are normally propriate frequency dividers.

When playing notes on the organ in the upper register, current frequencies of certain high harmonics thereof are not supplied to -the gang switches corresponding to such playing keys since they .are inaudible. Also, the scope of the instrument `may be deliberately limited to synthesizing voices wh-ich do not require certain frequencies, which frequencies therefore may not -be supplied to the several gang switches 10 in such an instrument.

It is therefore seen that the number of movable contacts 12 in the stacks used in a gang switch 10 may be varied in accordance with the voices the instrument is intended to produce, or even at the whim of the organ designer, and that the number of contacts shown in the gang switch 10 of FIG. 1 is therefore intended merely to be illustrative.

[As noted above, the voice mesh shown in detail in FIG. 2 illustrates a voice mesh for the great manual of an organ, a separate voice mesh being provided for each keyboard. The indicated harmonic signal input lines to the voice mesh are thus shown connected respectively through the amplifiers 60 to the above described set of bus bars associated with all of the stacks of contact members 12 associated with all of the playing keys of the great manual. The impedance elements, all shown in FIG. 2 as resistors, which form the connections between the various signal input lines and the various common conductors, enable tone signals of various intensities to be collected in such common conductors leading to the output, the greater the impedance of a particular resistor, the lower the intensity of the signal received by the common conductor from that parti-cular signal input line. Thus, the voice produced from the various frequency combinations in any of the common conductors leading to the output may be readily varied by changing the value of one or more of the resistors, and the ultimate determination of the several resistor values is therefore usually made by the organ designer who is familiar with the true sounds of the various voices that are to be synthesized.

In the voice mesh shown in FIG. 2, which of course is only illustrative, the various resistors have the following values in ohms.

Resistor value: Resistor number 27K R63, R102, R184.

39K R85, R106, R118, R136, R137,

56K R87, R93, R94, R107, R121.

82K R82, R96, R124, R147, R153, R156.

120K R68, R113, R163.

180K R88, R83, R84, R86, R97, R108,

R111, R117, R122, R132, R138, R141, R164, R116, R171, R177, R178, R183, R186, R187.

270K R98, R99, R129, R139, R142, R143,

R157, R158, R173, R188.

390K R101, R109, R112, R119, R123, R131, R148, R149, R159, R167, R179.

The resistor values given above for the voice mesh of FIG. 2 are suitable for use in the circuits of FIG. 1 wherein amplifiers 60 are used which lhave a low impedance output, such as transistor amplifiers. If amplifiers are not used, the values of the resistors should be adjusted to suit the impedance of the signal sources, in well known manner.

In operation of the system illustrated in the drawings, the tone signal generators 40-53 are first energized, t-he generators providing tone signals having frequencies corresponding to the fundamental and various harmonics noted in relation to the bus bars with which the generators are respectively associated. Thereafter, by pressing the playing key 38 for the note A4 in the great manual, all

of the contacts of the gang switch 10 are closed and the said tone signals are impressed respectively on the bus bars 14-27, whence the signals pass through the respective ampliiiers 60 `to the harmonic signal input lines 61, 66, 80, 91, 103, 114, 126, 133, 144, 151, 161, 168, 174 and 181 of the voice mesh.

If the player then wishes to sound any of the indicated voices, e.g., the sixteen-foot Bourdon, the eight-foot Open Diapason, the four-foot Gedeckt, and the eight-foot Trumpet, he manipulates the tablet switches 192, 205, 199 and 196 vto bring the respective switch blades thereof into engagement with the .lower contacts of the switches, whereby the respective tone signals are conducted to the output. Thus, as each switch blade engagement with the said contact is completed, the particular voice is sounded, and each voice continues to be sounded as long as the tablet switch is in such `operative position.

To play crescendo, the player presses the pedal switch 224, the actuator 223 of which then moving the blades 207 of the switches 208-217 successively into engagement with their lower contacts, thereby sequentially completing all circuits between the respective conductors and the output which were not previously completed by operation of the voice tablet switches. The sequential order of completion of such circuits by the switches 208-217 is from the top to the bottom in FIG. 2, i.e., the blade of switch 217 is first moved into engagement with its lower contact, then that of switch 216, and so on. Thereafter, raising the pedal 224 removes such added voices in reverse sequential order. The player, of course, has complete control over the extent of the intervals between operation of the successive switches operated by the pedal 224.

For sforzando, the player energizes the solenoid 226 by closing switch 227, whereupon the solenoid armature lowers the actuator 223 in the manner described for crescendo, ybut extremely rapidly, so that blades 207 of all the switches 20S-217 are brought into engagement with their respective lower contact substantially simultaneously. Opening the switch 227 produces a reverse effect, with the actuator 223 being rapidly raised by the solenoid spring retracting the armature thereof. Voices being played as a result of the operation of the tablet switches 192, 193, 196-205 are of course notv affected by operation of the switches 208-217.

While I have shown and described a particular embodiment of my invention, it will be apparent that numerous modifications and variations may be made without departing from the underlying principles of the invention. I therefore desire, by the following claims, to include within the scope of the invention all such modifications and variations by which substantially the results thereof may be obtained by substantially the same or equivalent means.

I claim:

41. In an electrical musical instrument including electrical tone signal sources for providing tone signals having frequencies corresponding to notes of the even tempered musical scale and harm-onics thereof, and an output for said instrument including electroacoustical translating means, the combination of a plurality of bus bars for separately collecting from selected ones of said sources electrical tone signals utilized in the tones sounded as fundamentals and each of various harmonics thereof, a plurality of common conductors, means providing connections from each of said common conductors to a plurality of said bus bars, each of said connections between a bus bar and one of said conductors being through an impedance element, each of said conductors being connected to a first switch blade adapted to engage either a first contact connected to said output or an opposed contact connected to a second switch blade, said second switch blade being movable between a null position and an operative position in which the said blade engages a contact connected to said ouput in series with said first contact, whereby, when said second switch blade is in said operative position, tone signals in the associated conductor are conducted to said output regardless of which of said first mentioned pair of contacts is engaged by said first switch blade, and means for moving all of said second switch blades from said null position to said operative position in a given sequence and at intervals Within the control of the player.

2. The combination in accordance with claim 1, including means for moving all of said second switch blades from said null position to said operative position substantially simultaneously.

3. In an electrical musical instrument including electrical tone signal sources for providing tone signals having frequencies corresponding to notes of the even tempered musical scale and harmonics thereof, and an output for said instrument including electroacoustical translating means, the combination of a voicing mesh connected to said signal sources and including a plurality of conductors for combining selected ones of said signals of different frequencies and in selected intensities, each of said conductors being connected to a first switch blade adapted to engage either a first contact connected -to said output or an opposed contact connected to a second switch blade, said second switch blade being movable between a null position and an operative position in which the said blade engages a contact connected to said output in series with said first contact, whereby, when said second switch blade is in said operative position, tone signals in the associated conductor are conducted to said output regardless of which of said first mentioned pair of contacts is engaged by said first switch blade, and means for moving all of said second switch blades from said null from said null position to said operative position substantially simultaneously.

5. In an electrical musical instrument including electrical tone signal sources for providing tone signals having frequencies corresponding to notes of the even tempered musical scale and harmonics thereof, and an output for said instrument including electroacoustical translating means, the combination of a plurality of bus bars for separately collecting from selected ones of said sources electrical tone signals utilized in the tones sounded as fundamentals and each of Vari-ous harmonics thereof, and a plurality of common conductors, means providing connections from each of said common conductors to a plurality of said bus bars, each of said connections between a bus bar and one of said common conductors being through an impedance element, said impedance elements being 0f different values selected to apply different composite signals of different tone character to diierent ones of said common conductors, said common conductors being connected to said output respectively through individual switching means such that the signals on any number of said common conductors may be conducted simultaneously to said output, whereby a corresponding number of voices of said instrument may be played simultaneously. 

3. IN AN ELECTRICAL MUSICAL INSTRUMENT INCLUDING ELECTRICAL TONE SIGNAL SOURCES FOR PROVIDING TONE SIGNALS HAVING FREQUENCIES CORRESPONDING TO NOTES OF THE EVEN TEMPERED MUSICAL SCALE AND HARMONICS THEREOF, AND AN OUTPUT FOR SAID INSTRUMENT INCLUDING ELECTROACOUSTICAL TRANSLATING MEANS, THE COMBINATION OF A VOICING MESH CONNECTED TO SAID SIGNAL SOURCES AND INCLUDING A PLURALITY OF CONDUCTORS FOR COMBINING SELECTED ONES OF SAID SIGNALS OF DIFFERENT FREQUENCIES AND IN SELECTED INTENSITIES, EACH OF SAID CONDUCTORS BEING CONNECTED TO A FIRST SWITCH BLADE ADAPTED TO ENGAGE EITHER A FIRST CONTACT CONNECTED TO SAID OUTPUT OR AN OPPOSED CONTACT CONNECTED TO A SECOND SWITCH BLADE, SAID SECOND SWITCH BLADE BEING MOVABLE BE- 